Laser Mass Spectrometric Analysis of Organic Atmospheric Aerosols. 2. Elucidation of Urban Air Pollution Processes

The dynamic behavior of aerosol-bound polycyclic aromatic hydrocarbons (PAHs) and other polycyclic aromatic compounds (PACs) in urban air was studied over the course of several whole days, both next to a street with heavy traffic and in a city park. Two-step laser mass spectrometry, a highly sensitive and selective technique, allowed measurements with 15 min time resolution. Large variations in particle concentration and chemical composition were observed, reflecting the contributions from Diesel trucks and gasoline-powered cars to urban aerosols. These sources were clearly identified using specific mass spectral patterns. Photochemically induced decay of oxygenated polycyclic aromatic hydrocarbons (OPAHs) was observed to occur within only a few hours. Rapid speciation of aerosol-bound organic carbon is now possible to complement data on routinely monitored atmospheric pollutants.